Mathematics for IGCSE & O level - Circle Theorems (Section 3 - No. 1)
In a circle, what is the angle subtended at the center by a minor arc, if the angle subtended at the circumference by the same arc is 30 degrees?
15 degrees
30 degrees
60 degrees
90 degrees
解释
The angle at the center is twice the angle at the circumference, so 2 * 30 = 60 degrees.